The superiority of natural bristles over presently available synthetic bristles in cosmetic and other types of brushes has long been recognized. In particular, cosmetic brushes have traditionally been made either with (1) natural bristles such as goat's hair bristles or (2) synthetic filaments made, for example, from polyamides (such as nylon) and polyesters. Natural bristles have traditionally been used more extensively than synthetic bristles in such brushes.
The use of the natural bristles, however, has several significant drawbacks. Inconsistent supplies of natural bristles and unacceptable variations from one batch of bristles to another often impede manufacture of brushes having natural bristles. In addition, natural bristles must be treated for hygienic purposes to eliminate the presence of contaminants, such as lice and lice eggs. Even if properly treated, many individuals are nevertheless allergic to natural bristles.
In view of these problems associated with the use of natural bristles, various attempts have been made to replace natural bristles with synthetic materials. The use of synthetic bristles has also met with difficulties, however. Synthetic bristles tend to be much stiffer than natural bristles. In addition, synthetic bristles simply do not have the softness, texture and overall appearance of natural bristles. For example, even though attempts have been made to replicate the wavy appearance of a natural bristle, most such attempts have provided only an artificial symmetrical wavy appearance in synthetic bristles. As such, these attempts have served to exacerbate the unnatural look and feel of synthetic bristles.
In addition, use of some synthetic bristle brushes (especially those for applying mascara) has been found to cause irritation to sensitive eyes as the brushes were not made from bristles of a small enough diameter. Use of small-diameter bristles in cosmetic brushes has also been found to be unacceptable as the bristles pick up too little product and simply "dump" cosmetic product onto the skin.
For these reasons, it is highly desirable to develop a type of bristle that can be used in cosmetic and other brushes which feels like natural bristles to the skin, and is free from natural contaminants to eliminate the need for sterilization prior to manufacture.